ARCH-02: 77-line PurchaseCommitment + pricing helpers copy-pasted across 7-8 Azure service clients

[cristim]

Severity: P2. Confidence: high.

Affected files:

• providers/azure/services/database/client.go:287-364
• providers/azure/services/cache/client.go:289-364
• providers/azure/services/database/client.go:587
• providers/azure/services/cache/client.go:602
• providers/azure/services/internal/reservations/purchase.go:372

Evidence:
A diff of database vs cache shows the entire PurchaseCommitment body (guards, ParseTermYears, request-body map, token fetch, DoIdempotentPurchaseTwoStep call) is byte-identical except "SqlDatabase" -> "RedisCache" and Service: "sql" -> "redis". The same shape repeats across search, cosmosdb, compute, synapse, managedredis (7 service-client callers of DoIdempotentPurchaseTwoStep). azureTermString is duplicated character-for-character in 6 files; fetchAzurePricing is re-implemented in 5 clients, each with its own near-identical RetailPriceItem struct. Only the pagination loop was centralized, whose own doc comment concedes the copy problem.

Impact:
Seven copies of a money-path purchase function means any fix (the ARCH-01 enum fix, a new required field, idempotency change) must be applied 7 times; the two-step-flow PR LeanerCloud/cloud-commitments-cli#680 already had to touch 7 clients. Divergence has demonstrably begun (the issue-LeanerCloud/cloud-commitments-cli#1020 fail-loud pricing guard exists in 5 clients but not managedredis/synapse).

Recommendation:
Extract a shared reservations.BuildPurchaseBody(...) plus a shared PurchaseCommitment template into providers/azure/services/internal/reservations (where DoIdempotentPurchaseTwoStep already lives); move azureTermString and a generic RetailPriceItem + fetchAzurePricing wrapper next to pricing.FetchAll.

Verifier verdict: confirmed - duplication and LeanerCloud/cloud-commitments-cli#1020-guard divergence verified byte-level; corrected the caller count to 7 (savingsplans uses a separate flow); the unmitigated layer is exactly the request-body construction where the PR-LeanerCloud/cloud-commitments-cli#1047-class enum literals live.

Source: docs/reviews/codebase-review-2026-06-10.md (automated multi-dimension code review, adversarially verified for P1/P2)

Findings from the 2026-09-02 codebase audit

Added by an automated audit of 3c0f8ac94048a2c36fce5ccddee54e6c4849a5cd (tip of origin/main). Each item below was reported by one reviewer and independently confirmed by a second that did not write it. Full report: docs/audits/codebase-audit-2026-09-02.md.

A15-008 (low)

Two updates on the helper half of this issue, both of which change what a fix has to touch. First, azureTermString is declared in exactly six packages (cache/client.go:591, compute:757, cosmosdb:589, database:609, managedredis:511, search:502), but synapse makes seven: it recomputes the identical rule inline at synapse/client.go:458-461 rather than calling a helper, so a name-based search under-reports it. All seven encode the Retail Prices API's "1 Year" / "N Years" spelling, so a fix landed only on the named copies leaves extractSynapsePricing silently finding no reservation price if that spelling ever changes. All seven clients already import providers/azure/internal/pricing, so the shared home is reachable without a new dependency. Second, on the pricing types: cache, cosmosdb, database and managedredis now alias pricing.RetailPriceItem, but synapse declares its own SynapseRetailPriceItem (client.go:110-122) omitting both Location and UnitOfMeasure, and search re-declares the envelope (:115-119) instead of aliasing pricing.Page. A field added to the shared item -- unit of measure is the one currently wanted -- decodes to zero in those two. (audit findings A15-008 and A08b-040)